The present application is related to a U.S. patent application entitled xe2x80x9cPositive Pressure Protective Helmetxe2x80x9d by the same inventor and filed on an even date herewith.
The present application is also related to a U.S. patent application entitled xe2x80x9cProtective Helmet with Selectively Covered Aperturexe2x80x9d by the same inventor and filed on an even date herewith.
The entire disclosures of the above mentioned applications are hereby incorporated by reference in their entirety.
The present invention relates generally to protective helmets. More particularly, the present invention relates to protective helmets for use when operating recreational vehicles.
In the field of recreational vehicles (e.g., motorcycles, all terrain vehicles (ATVs), snowmobiles, sport trucks, dune buggies, sandrails, and the like) protective helmets are often worn to protect the user""s head. Particulates such as sand and dust may enter the helmet during use and interfere with the user""s ability to operate the vehicle. The more particulates a helmet keeps away from the user""s face and eyes, the more comfortable the user will be. Even a few particulates in a user""s eye may cause great discomfort.
Protective helmets are typically subjected to standardized performance tests to ensure the user is as safe as possible if a collision occurs. The Department of Transportation (DOT) and Snell are two major organizations that set safety standards for crash-helmets in the United States. DOT sets minimum standards for all helmets designed for motorcyclists and other motor vehicle users. The standard is Federal Motor Vehicle Safety Standard 218 and is codified at 49 C.F.R. xc2xa7571.218. The Snell 2000 Standard for Protective Headgear establishes performance characteristics for helmets for use in open motorized vehicles such as motorcycles, ATVs, and snowmobiles.
The DOT subjects crash-helmets to an impact attenuation test. Impact attenuation is determined by measuring the acceleration experienced by a helmeted test headform during a collision. The helmeted headform is dropped on both a hemispherical and flat steel anvil. The height for the helmet and test headform combination fall onto the hemispherical anvil is set so that the impact speed is 5.2 m/sec. The minimum drop height is 138.4 cm. The guided freefall drop height for the helmet and test headform combination unto the flat anvil is set so that the minimum impact speed is 6.0 m/sec, with a minimum drop height of 182.9 cm.
When an impact attenuation test is conducted as described above, the following criteria are used to determine if a helmet passes; the test headform must not experience a peak acceleration over 400 G, accelerations in excess of 200 G must not exceed a cumulative duration of 2.0 milliseconds, and accelerations over 150 G must not exceed a cumulative duration of 4.0 milliseconds. The Snell impact management test involves a series of controlled impacts. First, the helmet is positioned on a head test platform. The helmeted headform is then dropped in guided falls onto test anvils. The impact energy must be a minimum of 150 Joules. If the peak acceleration imparted to the headform exceeds 300 G, the helmet fails.
The present invention relates generally to protective helmets. More particularly, the present invention relates to protective helmets for use when operating recreational vehicles (e.g., motorcycles, all terrain vehicles (ATVs), snowmobiles, sport trucks, dune buggies, sandrails, and the like). A protective helmet in accordance with an exemplary embodiment of the present invention comprises a first shell piece defining a head space and a second shell piece detachably attached to the first shell piece at an interface.
In accordance with one feature of the present invention, the interface has a pre-selected separation force. In some advantageous implementations, the pre-selected separation force of the interface is selected so that the second shell piece separates from the first shell piece when a pre-selected force is applied across the interface. In certain implementations, the pre-selected force less than a force required to dislodge a vehicle rider from a vehicle. Some embodiments of the present invention also feature a water tight seal formed between the first shell piece and the second shell piece.
In some embodiments of the present invention, the interface comprises a plurality of fasteners. Examples of fasteners which may be suitable in some applications include hook and loop fasteners, snaps, threaded fasteners, and pins. In certain embodiments, each fasteners comprises a shaft. This shaft may be advantageously adapted to break when a pre-selected breaking force is applied thereto. In some embodiments, the pre-selected breaking force is an axial force. In other embodiments, the pre-selected breaking force is a shear force. In some case, a diameter of the shaft may be dimensioned so that the shaft breaks when the pre-selected breaking force is applied to the shaft.
The first shell piece and the second shell piece may define a channel in some embodiments. When this is the case, a blower may be advantageously arranged for urging air into the channel. For example, the blower may draw air from the atmosphere outside the helmet and forcing the air into the air channel defined by the first shell piece and the second shell piece.
The second shell piece is defines the top portion of a channel while the second shell piece is detachably attached to the first shell piece. In an exemplary implementation, the second shell piece comprises a first edge flange and a second edge flange. The flanges preferably contact the first edge and second edge of the first shell piece to help detachably attach the first shell piece and the second shell piece. The second shell piece also comprises an intermediate portion which has a curved shape in lateral cross-section and which extends between the first edge flange and the second edge flange. In some advantageous implementations of the present invention, the first shell piece has sufficient strength to pass the DOT and Snell impact management tests whether or not the second shell piece is detachably attached. This may be accomplished by providing a wall of first shell piece having a desired combination of material strength and wall thickness.